Rob Ford has faced frequent health issues while in office

Mayor Rob Ford has spent a week in hospital, over which time doctors have determined that he has a malignant tumour that must be treated.

The discovery is the latest in a series of health issues that have afflicted the mayor, who has already sought care in a hospital at least twice this year.

Ford, who turned 45 in May, spent four days in hospital this spring, immediately before he entered a residential treatment program for substance abuse.

Ford's journey into rehab followed a year in which he was accused of and eventually admitted to having smoked crack cocaine. He also admitted to drinking to the point of putting himself in "drunken stupors" and vowed to cease drinking.

After his two-month stint in rehab, Ford came back to work just ahead of Canada Day. But he visited a hospital again in mid-July, to deal with what was said to be a toe injury that had been bothering him for some time. He was supposed to be having surgery for that after the upcoming Oct. 27 election.

In 2012, Ford spent two days at Humber River Hospital for a throat infection that had aggravated his asthma. A photo was tweeted showing the mayor reading a document in his hospital bed.

In February 2011, just a few months after he was formally sworn in as mayor, Ford twice went to hospital to deal with issues relating to kidney stones.

Ford had also been to hospital the year before he was elected mayor, as a result of appendicitis.

While the mayor told a TV station several years ago that he had "major surgery" on his appendix, in which a piece of his colon was removed because of a tumour, Dr. Zane Cohen has said that procedure resulted from the inflammation of his appendix.

"He did not have a tumour of the appendix," Cohen said.

Earlier in his term as mayor, Ford launched a high-profile campaign, in which he sought to lose weight. He began his so-called "Cut the Waist" challenge at a weight of 330 pounds in January 2012. Five months later, he weighed 313 pounds.